Tetraphosphorus hexafluoride and method for production and stabilization thereof

ABSTRACT

The novel compound tetraphosphorus hexafluoride (P4F6) is prepared by subjecting P2F4 gas to a high temperature and low pressure and collecting the resultant products on an adjacent surface which is maintained at liquid nitrogen temperature. The collected deposit is then warmed to room temperature to volatilize the various components therein, and the P4F6 is separated and collected by low-temperature fractional distillation. P4F6 dissolved in carbon disulfide is stabilized at room temperature.

United States Patent David Solln Berkeley, Calif.

June 16, 1969 The United States of America as represented by the Secretary of the Army lnventor AppL No. Filed Patented Assignee TETRAPHOSPHORUS HEXAFLUORIDE AND METHOD FOR PRODUCTION AND Solan et al., The Thennal Dissociation of Diphosphoros Tetrafluoride and the Formation of Tetraphosphrus Hexafluoride," Chemical Communications, No. 23, Dec. 4, 1968, pp. 1540-41 Primary Examiner-Oscar R. Vertiz Assistant Examiner-G. Alvaro Attorneys-Harry M. Saragovitz, Edward J. Kelly, Herbert Berl and Robert P. Gibson ABSTRACT: The novel compound tetraphosphorus hexafluoride (ER) is prepared by subjecting P P, gas to a high temperature and low pressure and collecting the resultant products on an adjacent surface which is maintained at liquid nitrogen temperature. The collected deposit is then warmed to room temperature to volatilize the various components therein, and the P.,F is separated and collected by low-temperature fractional distillation. P dissolved in carbon disulfide is stabilized at room temperature.

TETRAPHOSPHORUS HEXAFLUORIDE AND METHOD FOR PRODUCTION AND STABILIZATION THEREOF The invention described herein may be manufactured, used,

and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to the novel compound P F method of preparation and stabilization thereof.

It is an object of this invention to provide and disclose the novel compound P F It is a further object of this invention to provide and disclose a method for the preparation of PJ-" I It is a further object of this invention to provide and disclose a method for the stabilization of P P at room temperature.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims.

Tetraphosphorus hexafluoride is prepared by passing P P, gas at a rate of about 0.4 millimole per minute through a furnace heated to a temperature of approximately 750 to 950 C. and pressures of 2 or 3 torr. The resultant products pass from the furnace by a collision-free path and are collected on an adjacent surface which is maintained at liquid nitrogen temperature, e.g., 77 K. The condensation process must be carried out immediately upon the exit of the products from the furnace at external pressures not exceeding 100 millitorr. The collected deposit is then warmed to room temperature to volatilize undesired byproducts. Any remaining volatiles can be removed by condensing P P, on a surface which is maintained at -60 C.

The P 5 was identified through the utilization of mass specta, nuclear magnetic resonance, and infrared in an inert gas matrix. The structure was found to be: P(PF It was discovered that larger yields of P P may be obtained even at lower temperature when the PJ, gas is mixed with a large excess of an inert material, e.g., xenon at a 5-to-1 ratio by volume. It was also found that impure samples of P P. e.g., containing PF,I, may be utilized without any interference in the production of P F It is believed that the P F forms at the liquid nitrogen cooled surface by a series of reactions of PF radicals formed in the furnace itself.

The furnace utilized was cm. in length and had an exit bore of 2 mm. in diameter. In addition, it was composed of quartz and resistance heated by means of a tantalum wire wound around the furnace. The liquid nitrogen cooled surface was positioned approximately 7 cm. away from the exit of the furnace.

P,F is a solid below 68 C. However, it supercools readily to temperatures C. At temperatures above 68 C., it is a viscous, oily, clear liquid. However, it may have a black or orange-yellow tinge due to decomposition. It is quite stable in the liquid phase to about 0 C. Above 0 C. in the liquid phase, P F decomposes rapidly to PE}, and phosphorus fluoride polymers. It decomposes in the gas phase at pressures above 10 millitorrs readily at all temperatures. The gas phase decomposition is catalyzed by the presence of greases. The vapor pressure of P F has not been measured, owing to its decomposition in the gas phase, but probably does not exceed 3 torr at 0 C.

P P fumes in air, although it does not spontaneously catch fire as it oxidizes. It decomposes completely in sodium peroxide solution. When dissolved in acetonitrile, and warmed to room temperatures, it decomposes to PF; and phosphorusfluoride polymers. However, a solution of P F in carbon disulfide was found to be completely stable at room temperature. When a solution of P F dissolved carbon disulfide was brought into contact with air, voluminous white fumes were given ofi and the P P}, rapidly decomposed to phosphorusfluorine polymers or phosphorus oxides. Such a solution could be utilized as an initiator or catalyst for a free radical chain mechanism or polymerization process or as a herbicide. The solution could also be used as an oxygen getter for reactions in carbon disulfide.

Although I have described my invention with a certain degree of partic ularit I wish it to be understood that I do not desire to be limite to the exact conditions shown and described, for obvious modifications will occur to a person skilled in the art.

Having described my invention, I claim:

1. The compound P P having the structure P( PE),

2. A method for the production of P F comprising; the subjection of P P, gas to a temperature of around 750 C. to 950 C. at low pressures, contacting the resultant roducts with an adjacent surface maintained at liquid nitrogen temperature to form a deposit on said surface, warming the collected deposits to room temperature to remove volatiles, and collecting the P by low temperature fractional distillation.

3. A method in accordance with claim 2 wherein the P l gas is mixed with xenon in a l-to-S ratio by volume.

4. A method in accordance with claim 3 wherein the P P gas contains PF 1 as an impurity.

5. A solution consisting of P F dissolved in carbon disulfide without exposure to air.

6. A solution in accordance with claim 5 wherein the solution is maintained at room temperature. 

2. A method for the production of P4F6 comprising; the subjection of P2F4 gas to a temperature of around 750* C. to 950* C. at low pressures, contacting the resultant products with an adjacent surface maintained at liquid nitrogen temperature to form a deposit on said surface, warming the collected deposits to room temperature to remove volatiles, and collecting the P4F6 by low temperature fractional distillation.
 3. A method in accordance with claim 2 wherein the P2F4 gas is mixed with xenon in a 1-to-5 ratio by volume.
 4. A method in accordance with claim 3 wherein the P2F4 gas contains PF2I as an impurity.
 5. A solution consisting of P4F6 dissolved in carbon disulfide without exposure to air.
 6. A solution in accordance with claim 5 wherein the solution is maintained at room temperature. 